on the Generation of Animal Heat, 415 



the body is raibed above tlie natural standard, to which it 

 falls when the constitution returns to its natural state, and 

 the secretions are restored. 



It has been observed, by a distinguished chemist, that 

 " the experiments to determine the specific heat of tlie 

 blood are of so very delicate a nature, that it is difficult to 

 receive them v,'ith perl'ecl confidence*," The experunents 

 of Dr. Crawi'ord for this purpose were necessarily made on 

 blood out ol tbe body, and at rest. Now, when blood is 

 taken from the vessels, it immediately undergoes a remark- 

 able chemical chanse, separating into a solid and a fluid 

 part. This separaticn is not complete for some time ; but 

 whoever takes the pains to make observations on the sub- 

 ject, can hardly doubt that it begins to take place imme- 

 diately on the blood being drawn. Can experiments on 

 the blood, under these circumstances, lead to any very sa- 

 tisfactory conclusions, respeelmg tht^ specific heat of blood 

 circulating in the vessels of the body? The diluting the 

 blood with large quantities of water, as proposed by Dr. 

 Crawford, does not altogether remove the objection ; for 

 this only retards, it does not prevent coagulation ; and some 

 time nuist, at any rate, elapse, while the blood is flowing 

 and the quantity is being measured, during which the se- 

 paration of its solid and fluid parts will have begun to take 

 place. 



More might be said on this subject ; but I feel anxious to 

 avoid, as much as possible, controversial discussion. It is 

 my wish not to advance opinions, but simply to state some 

 facts which I have met with in the course of mv physiolo- 

 gical investigations. These facts, I am willing to hope, 

 possess some value ; and they may perhaps lead to the de- 

 velopment of other facts of nuich greater importance. 

 Physiology is yet in its infant state. It en^braces a great 

 number and variety of phaenomena, and of these it is very 

 difficult to obtain an accurate and satisfactory knovvledoe ; 

 but it is not unreasonable to expect, that by the successive 

 labours of individuals, and the faithful register ot their 

 observations, it may at last be enabled to assume the form 

 of a more perfect science. 



• Thomson's History of the Royal Society, p. 120. 



LXXIII. On 



